Two species of Trichinella were identified from China by means of PCR amplification of the mitochondrial small subunit ribosomal DNA and the expansion segment V region of the ribosomal DNA. Seven isolates originating from domestic pig and one isolate originating from dog showed identical DNA banding pattern to Trichinella spiralis, and two isolates from dog showed DNA banding pattern identical to Trichinella nativa. Sequence analysis of the 5S rDNA inter-gene spacer region from the ten Trichinella isolates confirmed the existence of only two Trichinella species and revealed the inner species genetic variation within T. spiralis and T. nativa.